Just checking that that's how this works. I refer to the rule that you can only use one damage reducing or ignoring power or ability. So, he can't use both Impervious and Adapative Armor at the same time, right?

M10 Iron Man has:

Adaptive Armor When Iron Man would take damage from a character assigned a relic or resource, Iron Man ignores that damage and rolls a d6. On a result of 1-3, deal Iron Man 1 unavoidable damage. This ability can't be ignored.

So, when Iron Man is on an Impervious click and an opposing character with a relic or resource deals him 3 damage, Iron Man has two choices:

(1) Roll on Impervious. There's a 2 in 3 chance that he takes 1 damage, and a 1 in 3 chance that he takes 0 damage.
(2) Use Adaptive Armor. There's a 1 in 2 chance that he takes 1 damage and a 1 in 2 chance that he takes 0 damage.

Naturally, he wouldn't roll on Impervious since he's got a better chance with Adaptive Armor to take no damage. But if an opponent does mistakenly roll for Impervious, then they can't roll for Adaptive Armor, right?

He doesn't roll until he would TAKE damage. That is after damage is dealt and after you would normally have to choose between reducers (or between a reducer and ignoring damage dealt).

The rule you refer to does not limit ignoring damage taken. He can use his Impervious and Adaptive Armor just fine together.

As Normal pointed out, Iron Man's armor affects damage taken, not damage dealt.